Iron's desire to mingle means chemistry's right to clean up

Tiny particles of ultra pure iron, each as small as a billionth of a metre, are being developed by Sydney researchers as a new weapon to fight pollution.

If it works, nanoparticles of iron could be used to sweep clean contaminated industrial sites, filter agricultural chemicals from water running off farms, and even recycle drinking water for cities.

The extraordinary potential of iron nanoparticles, said David Garman, executive director of the Co-operative Research Centre for Waste Management, "has got us extremely excited".

When something made of iron is left outdoors it quickly starts to rust or oxidise. It is iron's overwhelming desire to react with the environment that the scientists are confident can be harnessed.

Dr Garman said that when contaminated water flowed through iron "nano-dust" the metal reacted with the pollution, causing it to break down harmlessly.

"We can produce particles for cleaning herbicides and pesticides," he said, predicting nano-dust would be particularly valuable in treating farm run-off.

"We are also moving towards cleaning water for reuse." But first his team, based at the University of NSW, had to overcome a challenge - producing almost unimaginably tiny pure iron particles.

"Iron normally occurs in great lumps . . . or in big ingots," Dr Garman said. "The holy grail has become producing these particles smaller, and more cheaply."

But pure iron is so reactive it wants to react straight away, long before it can be sent into battle against any pollutant. "It is very hard to grind iron down because to do that you have to heat it, and when you heat it, it oxidises," Dr Garman said.

His team has found a way to produce pure iron nano-particles, and at a tenth the cost of American production, where it is now being made for $US45 ($63) a kilogram. "It puts Australia at the forefront of the research."

He said his centre would soon be producing iron nano-dust by the kilogram. "Later on we expect to make tonnes."

Eventually, he predicted, iron particles could be teamed with biological pollution fighters, also being developed by his centre, to fight even more complicated toxins.

Exactly how much of the iron nanoparticles would be needed would depend upon the size and nature of each project, Dr Garman said. However, as little as one kilogram could be enough to treat an area of about 10 square metres.

The first major test of the potential of iron nano-dust is expected to be launched next year.

During the six-month trial the Sydney scientists hope to use iron nanoparticles to trap and break down industrial chemicals - blamed for causing nervous system disorders, liver and kidney disease, lung problems and possibly even cancer - discovered in ground water flowing under a former Sydney factory site.